1. Field of the Invention
The present invention relates to a disc player capable of conducting a playback of a disc memory medium (hereinafter referred to as "disc") for use in CD, LD, MD, CD-ROM, MO and the like. More particularly, the present invention is concerned with a disc player having unnecessitated a switch for detecting the signal-recording inner circular end of the disc, etc., to thereby enable simplifications of the structure and control thereof.
2. Discussion of Related Art
Generally, the disc player achieves a playback by having a light pickup read disc information upon the input of initialization signal. This playback is conducted by the move of the light pickup from the signal-recording inner circular end to the circumference of the disc in the radial direction of the disc. Therefore, the light pickup not only should reach the signal-recording inner circular end of the disc but also should detect the arrival at the signal-recording inner circular end prior to reading of information.
For meeting the above requirement, a switch capable of mechanically or optically detecting light pickup is disposed at a site inside the conventional disc player which corresponds to the signal-recording inner circular end of the disc, and the arrival of the light pickup at the signal-recording inner circular end of the disc is determined on the basis of the signal detected by the detection switch. Further, the disc player is provided with a set detecting sensor capable of checking the setting of the disc on the turn table and with a diameter determining sensor capable of detecting the size of the diameter of the disc, thereby having a structure capable of preventing malfunctions.
The conventional disc player is provided with the detection switch for detecting the arrival of the light pickup at the signal-recording inner circular end of the disc, so that not only is its structure complex but also it is required to accurately arrange the detection switch, thereby rendering the assembly thereof time-consuming. Moreover, the playback of the disc is conducted in accordance with the detection signal from the detection switch, so that not only is the control system complex but also appropriate detection signal cannot be outputted, for example, when the detection switch is in trouble or has suffered from dislocation. In this instance, there occur disadvantages such as the failure to playback the disc or the malfunctioning. In addition, the conventional disc player needs the sensor for detecting the setting of the disc, the sensor for determining the diameter of the disc, etc., which further renders the structure complex and renders the control system complicated.